ARM: realview/vexpress: consolidate SMP bringup code

Realview and Versatile Express share the same SMP bringup code, so
consolidate the two implementations.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 104 insertions, 0 deletions

diff --git a/arch/arm/plat-versatile/platsmp.c b/arch/arm/plat-versatile/platsmp.c
new file mode 100644
index 000000000000..ba3d471d4bcf
--- /dev/null
+++ b/arch/arm/plat-versatile/platsmp.c
@@ -0,0 +1,104 @@
+/*
+ *  linux/arch/arm/plat-versatile/platsmp.c
+ *
+ *  Copyright (C) 2002 ARM Ltd.
+ *  All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/jiffies.h>
+#include <linux/smp.h>
+
+#include <asm/cacheflush.h>
+
+/*
+ * control for which core is the next to come out of the secondary
+ * boot "holding pen"
+ */
+volatile int __cpuinitdata pen_release = -1;
+
+/*
+ * Write pen_release in a way that is guaranteed to be visible to all
+ * observers, irrespective of whether they're taking part in coherency
+ * or not.  This is necessary for the hotplug code to work reliably.
+ */
+static void __cpuinit write_pen_release(int val)
+{
+        pen_release = val;
+        smp_wmb();
+        __cpuc_flush_dcache_area((void *)&pen_release, sizeof(pen_release));
+        outer_clean_range(__pa(&pen_release), __pa(&pen_release + 1));
+}
+
+static DEFINE_SPINLOCK(boot_lock);
+
+void __cpuinit platform_secondary_init(unsigned int cpu)
+{
+        /*
+         * if any interrupts are already enabled for the primary
+         * core (e.g. timer irq), then they will not have been enabled
+         * for us: do so
+         */
+        gic_secondary_init(0);
+
+        /*
+         * let the primary processor know we're out of the
+         * pen, then head off into the C entry point
+         */
+        write_pen_release(-1);
+
+        /*
+         * Synchronise with the boot thread.
+         */
+        spin_lock(&boot_lock);
+        spin_unlock(&boot_lock);
+}
+
+int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
+{
+        unsigned long timeout;
+
+        /*
+         * Set synchronisation state between this boot processor
+         * and the secondary one
+         */
+        spin_lock(&boot_lock);
+
+        /*
+         * This is really belt and braces; we hold unintended secondary
+         * CPUs in the holding pen until we're ready for them.  However,
+         * since we haven't sent them a soft interrupt, they shouldn't
+         * be there.
+         */
+        write_pen_release(cpu);
+
+        /*
+         * Send the secondary CPU a soft interrupt, thereby causing
+         * the boot monitor to read the system wide flags register,
+         * and branch to the address found there.
+         */
+        smp_cross_call(cpumask_of(cpu), 1);
+
+        timeout = jiffies + (1 * HZ);
+        while (time_before(jiffies, timeout)) {
+                smp_rmb();
+                if (pen_release == -1)
+                        break;
+
+                udelay(10);
+        }
+
+        /*
+         * now the secondary core is starting up let it run its
+         * calibrations, then wait for it to finish
+         */
+        spin_unlock(&boot_lock);
+
+        return pen_release != -1 ? -ENOSYS : 0;
+}